Parasitoid wasps are abundant free-living insects that inject venom into and then lay their eggs on other insects. Parasitoids vary in hosts they utilize (flies, beetles, butterflies, etc), the life stage they parasitize (eggs, larvae, pupae), and whether their eggs are laid and develop within or outside the host. Due to this diversity, parasitoid venoms have evolved different mechanisms for manipulating host immunity, physiology and behavior in ways that enhance development of the parasitoid young. Among their effects, venoms can induce temporary or permanent paralysis, selective apoptosis, and alterations in host lipid physiology, immunity, and behavior. Yet virtually nothing is known about the diversity or function of individual parasitoid venom proteins. There are over 150,000 species of parasitoids. The model parasitoid Nasonia vitripennis alone has at least 79 different venom genes, of which 24 have no sequence similarity to any known proteins and contain no known conserved domains. Given their incredible number and diversity, parasitoids venoms represent an immense and untapped potential resource for drug discovery. The challenge is to efficiently assess this immense potential pharmacopeia for molecules with medical and research applications. Small biologically active peptides are particularly promising as therapeutic agents, and therefore their detection in parasitoid venoms is an important goal. We predict that evolutionary conservation in novel venom proteins can be used to identify short peptides with biological activity of relevance to medicine and research. If correct, this approach could rapidly accelerate new drug discovery among the immense pool of parasitoid venom proteins. Here we propose to investigate (a) the effects of individual Nasonia venom proteins in the whole animal Sarcophaga bullata (flesh fly) and in human cell lines by transcriptome, proteome, and physiological profiling, (b) assess the diversity of evolution of parasitoid venoms and identify conserved short peptides, and (c) test the hypothesis that evolutionary conservation can be used to predict short bioactive peptides, using our whole animal and human cell line assays. The project combines genetic, proteomic, physiological and evolutionary approaches to explore function, diversity, and potential for drug discovery in the immense pool of parasitoid venom proteins.